Trip and shear mechanism



July 25, 1961 L. H. VINING, JR., 'ETAL 2,993,442

TRIP AND SHEAR MECHANISM Filed Jan. 7, 1960 2 Sheets-Sheet 1 FIGZ.

FIGJ.

N 8 R INVENTOR L.HEATH vmme, JR. ANTON H. ERICKSON ALBERT s. WILL IATTORNEYS July 25, 1961 L. H. VINING, JR, ET AL 2,993,442

TRIP AND SHEAR MECHANISM 2 Sheets-Sheet 2 Filed Jan. 7, 1960 Q I Q Vang/ 7mm I I I v INVENTOR. L.HE VINING,JR.

ANTON H. CKSON ALBERT S. WILL l BY TTORNEYS,

2,993,442 TRIP AND SHEAR MECHANISM L. Heath Vining, Jr., Fairfax, Va., and Anton H. Erickson, Silver Spring, and Albert S. Will, West Hyattsville, Md., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Jan. 7, 1960, Ser. No. 1,142 Claims. (Cl. 102-70.2)

This invention relates to direct action fuzes for projectiles, more particularly to a time delay safety device for arming the fuze while the projectile is in flight.

In firing shells from artillery weaponsit is desirable to provide a fuze for the projectile which will only be armed after a predetermined time in flight and will detonate upon impact.

With direct action fuzes as hitherto known, it has been the usual practice to place the fuze charge which is to be detonated by the striking pin as far back in the fuze as possible to allow sufiicient clearance for the pin to avoid detonating upon accidental impact. Placement of the fuze charge in the rear part of the fuze generally has the disadvantage that it entails the use of a long striking pin which in turn delays the setting off of the fuze charge. This delay is primarily due to shock or pressure wave formed by the impact experienced by the projectile and acting upon the striking pinso that a certain period of time must elapse before the pin can ignite the fuze charge. Should the projectile graze or ricochet the shock wave may travel along the wall of the projectile for a considerable distance before the fuze charge is ignited. Such a shock wave may result in serious damage to the projectile.

It will now be apparent that it would be highly desirable to obtain a direct action fuze charge that could be located in the rear of the fuze and would be completely safe during initial handling and firing, arm itself during flight and would detonate upon impact.

Prior to the present invention it was not possible to have such a fuze because a striking pin was needed to strike the detonator in the nose of the projectile with the ever present danger of detonation by an accidental impact.

It is an object of this invention to provide a base mounted fuze that is normally unarmed until it is fired from a gun.

It is another object to provide a new and improved base mounted direct action fuze responsive to an impact.

It is a further object to provide a base fuze that will remain unarmed until after it has been fired from a gun and has travelled a predetermined distance.

It is a still further object to provide a safety mechanism for a base fuze that is responsive to rapid acceleration to thereby arm the fuze during the trajectory flight of the projectile.

Further objects and the entire scope of the invention will become more clearly apparent in the following detailed description and in the appended claims. The accompanying drawings display the general construction and operational principles of the invention, it is to be understood, however, that the drawings are furnished only by way of illustration and not in limitation thereof of which:

FIG. 1 is a sectional view of a fuze in the unarmed position and embodying the invention;

FIG. 2 is a sectional view of the invention similar to that shown in FIG. 1 with the fuze in the armed position;

FIG. 3 is a perspective view, being somewhat enlarged, of the arming device of FIG. 1; and

FIG. 4 is a schematic view of the arming and firing circuit of the fuze.

2,993,442 Patented July 25, 1961 Referring now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a base fuze 10 having a casing indicated by the numeral '11.

Fuze case 11 may be mounted in the base of a projectile 10 by screwing the threaded portion 12 into the base. Detonating charge 13 is located in the nose of the fuze and will be centrally located in the maincharge of the projectile when it is screwed into position. Detonating charge 13 is separated from the prime detonator 14 by a separator plate 15 which is permanently fitted in casing 11 and has an aperture 16 located medially therein thereby connecting the prime detonator 14 with the detonating charge 13. Located on the base side of the detonator is an acceleration responsive motor device 17 with a flatted shaft 18 for releasing a spring loaded primary trip assembly 19. The primary trip assembly 19 carries a secondary assembly 20 which is locked within sleeve member 21 by three steel balls 22 located in the sleeve member 21. Spring biased non-metallic plunger 23 is released when steel balls 22 reach the counter bore 24 which permits the balls to move outward thereby allowing the non-metallic plunger to slip past and sever the shorting wire 25 connected between terminal posts 26 and 27. The shorting wire 25 is connected across inertia actuated voltage generator 28 in parallel with electroresponsive detonator 29. The sleeve member 21, inertia generator 28, electroresponsive element 29 and terminal posts 26 and 27 are held in place by a potting material 30. The operation of applicants device will be described with particular reference to FIG. 3. Acceleration responsive motor device 17 has a rotatable eccentric disk 31 which has its center of gravity out of line with its axial center so that a moment of inertia is produced around the axial center when the disk is subjected to acceleration. The eccentric disk 31 has a chamber 41 extending through the heavy portion of the disk. The disk 31 is normally locked with the chamber 41 in a safe position, which is when chamber 41 is not aligned between electroresponsive detonator and the prime detonator. The disk is held in this position by stud 32 resting against one side of inertial member 33, spring biased by springs 34. When the fuze is subjected to acceleration inertial member 33 moves relative to the base compressing spring 34 thereby unlocking eccentric disk 31 for rotation in a clockwise direction as viewed in the figure until the chamber reaches an armed position where it is locked in place by a spring stud 42. The rate of rotation of the eccentric disk will be determined by an acceleration integrating device not shown. It is to be understood that any device for regulating the rate of rotation of the eccentric disk such as a timing mechanism may be utilized in place of the acceleration integrating device. As the disk 31 moves clockwise to the armed position in which chamber 41 is aligned with detonators 14-29 the flattened shaft 18 attached thereto rotates in aperture 35 of shaft 36 until the flatted shaft enters the longitudinal portion of inverted keyhole aperture 37 of shaft 36. When the flattened shaft 18 enters the longitudinal portion of inverted keyhole aperture 37 the primary trip assembly 19 including shaft 36, connector plate 38 and sleeve 21 are forced down, relative to FIG. 3, toward the base of the fuze. by compressed spring 39.

The sleeve 21 encases the secondary assembly 20 which.

includes non-metallic plunger 23 and a compressed spring 40. The secondary assembly is normally locked in place in the sleeve by three steel balls 22. As the primary assembly 19 continues to move toward the base the steel balls 22 in sleeve 21 are forced outward when the balls reach the counterbore portion 24 of the member 30 thereby unlocking and releasing the secondary assembly. The secondary assembly consisting of non-metallic plunger 23 moves out from its normal position under pressure of the compressed spring 40 to strike and sever shorting wire located between insulated spaced apart binding posts 26 and 27 thereby removing a short from the electroresponsive detonator and arming the fuze, as may be more clearly seen in FIG. 2. Upon impact of the projectile the inertia generator 28 of FIG. 2 generates a voltage by causing a permanent magnet 28 to move relative to the coil thereby firing the electroresponsive detonator 29 which activates the prime detonator 14 by passing the explosive gas through chamber passage 41, which activates the detonating charge of the fuze 13.

Referring to FIG. 4, it will be seen that should the inertia generator 28 produce a voltage due to unusual vibration or dropping the fuze, the electroresponsive element 29 will not fire until shorting wire 25 has been severed by plunger 23.

From the foregoing description it is submitted to be clearly apparent that applicant has provided a safety factor in direct action fuzes by the means disclosed herein. With the device in a safe position any voltage developed by the inertia generator is automatically short circuited by the shorting wire. If the wire should happen to break before the eccentric disk has moved to an armed position and the electroresponsive detonator should be detonated the electroresponsive detonator will be actuated without harmful effect because the chamber passage in the disk between the electroresponsive detonator and the prime detonator is out-of-line therewith. In brief the fuze can only be armed after it has been subjected to suflicient acceleration 'to release the acceleration responsive motor and causing the eccentric disk to be rotated to an armed position aligning the chamber between the electroresponsive element and the detonator. Concurrent therewith the shorting wire across the inertia generator must be removed. Thus the projectile will only be a lethal device during its trajectory path to the target.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed and desired to be secured by Letters Patent of the United States is:

l. A safety device for a direct action fuze for a projectile and comprising a base mounted detonating fuze charge, a prime detonator for igniting said fuze charge, an electroresponsive detonator connected to an inertia actuated voltage generator in parallel with a severable shorting means for rendering the said generator normally ineffective, an acceleration response device located between said prime detonator and said electroresponsive detonator and including a rotatable eccentric disk with its center of gravity diiferent than its axial center and having a chamber extending through said disk at its axial center, the chamber of said disc normally located in an unarmed position, a flattened shaft means connected to said disk at the axial center for locking and unlocking a spring biased primary device, said primary device normally located in a locked position and including a spring biased secondary means locked therein for arming said electroresponsive detonator, said secondary means including a spring biased non-metallic plunger which when unlocked by said primary device will interrupt said shorting means, whereby upon the projectile being accelerated the said eccentric disk of the acceleration responsive device develops a moment of inertia around the axial center causing the said disk to rotate to an armed position aligning the chamber with the electroresponsive detonator and the prime detonator, concurrently therewith said flattened shaft means unlocks said primary device to effect unlocking of said secondary means resulting in severance of said shorting means.

2. A direct action fuze for a projectile comprising in combination a fuze casing attachable to the base of a projectile, a fuze charge disposed within the casing at the forward end thereof, a prime detonator connected to said charge by a medially located chamber in a disk located therebetween, an electroresponsive detonator, said prime detonator being activated by the hot gases of said electroresponsive detonator when ignited, a severable shorting means for short circuiting said electroresponsive detonator, an inertia responsive voltage generator normally connected in parallel with said electroresponsive detonator and said shorting means, said generator generating a voltage sufficient to activate said electroresponsive detonator upon impact when said shorting means has been removed, an acceleration responsive means located between said electroresponsive detonator and said prime detonator comprising a rotatable eccentric disk with the center of gravity thereof different than its axial center and having a chamber medially extending through the diameter thereof, the chamber in said disk being normally in an unarmed position, a flattened shaft connected to said disk in alignment with the axial center thereof, a spring biased assembly means normally locked to said flattened shaft by an elongated slot for severing said shorting means, said assembly means being unlocked when the flattened shaft has rotated to fit in the elongated slot, whereby, upon said projectile being accelerated said eccentric disk develops a movement of inertia about the axial center causing said disk to rotate to the armed position such that the chamber is aligned with both said electroresponsive detonator and the prime detonating device and concurrently therewith the fiatted shaft is rotated unlocking said spring biased assembly means thereby severing said shorting means and arming the fuze in flight.

3. A fuze as recited in claim 2 wherein the shorting means comprises a fine severable wire held in tension between two rigid posts, and means located in the base of the fuze for supporting said posts in mutually insulated parallel relation in a position such that the wire is adapted to be severed by said spring biased assembly means.

4. A fuze as recited in claim 2 wherein said chamber passes through said eccentric disc at the axial center, a spring biased inertial member, a spring yieldably urging the member toward the forward end of the projectile, said disk having a stud located on an outer surface thereof and normally held in blocking engagement with said inertial member to prevent said disk from rotating from a safe position, whereupon the said fuze being accelerated the inertial spring biased member compresses the spring thus unblocking said disk for rotation until the said chamber reaches said armed position, and means including a spring biased stud for locking said disk in said armed position.

5. A fuze as recited in claim 2 wherein said spring biased assembly means comprises a spring biased shaft having means forming a substantially inverted keyhole shaped aperture engaged by said flattened shaft for locking said spring biased shaft in an initial position, said shaft being released for movement when the flattened shaft rotates sufliciently to enter the longitudinal portion of the substaniatlly inverted keyhole shaped aperture, a sleeve member connected to said spring biased shaft by a link connection, a chamber having said sleeve member at one end and said shorting means at the other end thereof, said chamber closely surrounding said sleeve member in such manner as to allow the sleeve member to move parallel to the axis of the projectile, said chamber having a counterbore portion starting from the midpoint thereof to said shorting means located at the other end of said chamber, said sleeve having a compressed spring and non-metallic shaft locked therein by means of steel balls located in the casing of said sleeve member whereby when said flattened shaft is rotated by said rotatable eccentric disc in said shaft aperture said flatt'ened shaft enters the longitudinal portion of the in;

References Cited in the file of this patent UNITED STATES PATENTS Jordan Oct. 20, Plurnley Jan. 1, Kroeger et a1 July 23, Ricker Jan. 19,

Olsen Apr. 26, 

